Injection pump



Aug. 20, 1963 J. HElsER 3,101,057

INJECTION PUMP Filed Deo. 5, 1961 United States Patent Oiiice` 3,101,057Patented Aug. 20, 1963 arenas? LUECTIGN PUMP Joachim Heiser, Bernhausen,Kreis Esslingen, Wurttemberg, Germany, assigner to Robert Bosch @.mbl.,Stuttgart, Germany Filed Dee. 5, 196i, Ser. No. 157,631 Claims priority,application Germany Dec. l0, 1%@

' v `7 Claims. (Cl. T33-37) The present invention relates to pumps.

M-ore particularly, the present invention relates to injection pumpsadapted to be used with internal combustion engines for supplying fuelto the cylinders thereof.

Although injection pumps are at the present time highly developed,nevertheless it is still necessary to provide two basic types ofinjection pumps. One type is" designed for operation `at relatively lowspeeds and the other type is designed for operation at relatively highspeeds. Injection pumps are required to operate at very high pressuresin order -to be able to 4transmit the fuel to the cylinders of theengine. Because of these high pressures there is always the problem ofpreventing fuel from leaking back to the inlet of the pump during thepressure strokes thereof. In pumps which are designed for slow speedoperation, this problem is taken care `of by providing in the pump avalve means which will reliab-ly -prevent yfuel from flowing back to theinlet of the pump during the pressure strokes thereof, but such pumpscannot be used `for high speed operation because the'inertia of thevalve means prevents the valve means from main-taining the inlet of thepump elo-sed olf from its pumping chamber during the entire part `ofeach pressure stroke. lt is therefore necessary at the present time toprovide -for high speed operation a pump which does not have such lavalve means and which is capable during 4high speed operation ofpreventing ilow of fuel back to the inlet of the pump. However, thesepumps which are designed yfor high speed operation cannot prevent iiowof fuel back to the inlet of the pump if these pumps operate at `arelatively low speed. The only wlay to prevent fuel from owing backtothe inlet of the pump with a pump which does not include a valve meansand which is designed for high speed operation is Ito provide the pumpwith cylinders and pistons of extremely large diameters to greatlyincrease the length of the path along which the fuel would have to iiowback to the inlet of the pump, and since it is essential that moderninjection pumps be quite small and compact, it is not feasible toprovide pumps of relatively large diameters fat their cylinders andpistons. f

It is, therefore, a primlary object of thepresent inven-` tion toprovide lan injection pump which is capable of operating both at Alowand at high speeds without any danger of leakage of fuel back to theinlet of Ithe pump during the pressure strokes thereof while at the sametime maintaining the dimensions of the pump relatively small and compactso that the pump of the invention while having a perfectly satisfactorysize enabling it to be used without diiliculty with modern engines atthe `same time can be used either for operations at relatively lowspeeds or for operations at relatively high speedsso that it becomesunnecessary to provide -two basically different pump designs dependingupon whether the pump is to operate -at low speeds or high speeds. l

Another object of the present invention is to provide an injection pumpwhich includes all of the best features of both the slow speed and thehigh speed designs while at the same rtime eliminating all of thedisadvantages thereof'.

Still another object of the present invention is to provide an injectionpump which is of an extremely simple design and which includes no moreparts than conventional pumps while at the `same tirne being capable ofoperation at -both low ,and high speeds without any danger of leakage offuel back to the inlet of the pump.

It is furthermore an object of the present invention to provide aninjection pump which is rugged and reliable in operation and which willbe capable of operating perfectly not only at relatively low and highspeeds but also with rall types of `fuels and under all operatingconditions.

With these objects in view, the invention includes, in an injection pumpwhich is adapted to operate at relatively low and at relatively lhighspeeds, a cylinder having in its interior a pumping chamber; an inletpassage means provides for flow of `fuel into the pumping chamber and adischarge passage means provides for flow of -fuel out of the pumpingchamber, and a piston means is located in lthe cylinder forreciprocation therein along pressure and 4suction strokes. A controlmeans cooperates with the cylinder for opening the inlet passage Vmeansduring each suction stroke of the piston means and for closing the inletpassage means during each pressure stroke of the piston means, and thiscontrol means opens the discharge passage means during each pressurestroke of lthe piston means a-nd closes the discharge passage meansduring each suction stroke of the piston moans. Under certain operatingconditions, as when thepump operates with a relatively light fuel or aswhen the parts become relatively worn, this control means is incapableof preventing leakage of fuel back to the inlet passage means when thepump operates at relatively low speeds. A valve means is located in thepath of fuel ilow through the inlet pas- -sage means to the pumpingchamber for closing olf the pumping chamber from the inlet passage meansduring the pressure strokes of the piston means when the pump opcratesat relatively low speeds, and thus, in accordance with the presentinvention, the control means and the valve means cooperate -to preventleakage of fuel back to the in- `let passage means during the pressure`strokes of the piston means when the pump operates at relatively lowspeeds and when the pump operates` at relatively high speeds.

The novel features which are considered as characteristic for theinvention yare set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, will-be best understood from the following description of a specificembodiment when read in connection with the accompanying drawing, inwhich one possible injection pump according to the present invention isillustrated in an axial sectional elevation with the discharge passagesof the pump shown in an axial sectional plane which is angularlydisplaced from the axial sectional plane in which the remainder of thestructure of the drawing is illustrated.

In the particular example which is illustrated in the drawing,` the pumpof the invention has one cylinder Land piston and it is designed tosupply fuel rto an engine of four cylinders, but it is to be understoodthat the invention is `applicable to pumps of any desired-number ofcylinders fand can supply fuel to engines having any desired number ofcylinders.

The pump illustrated in the drawing includes'a housing having a lowerpart 1 and an upper part 2 iixed to v the lower part I1. This lowerhousing part 1 rotatably supports the `drive shaft 3 of the pump, thisdrive shaft 3 being connected in a known way to the crankshaft of theengine so as to operate the pump in proper synchronism' with the engine.The drive shaft 3 iixedly carries at its upper end, Ias viewed in thedrawing, a cam 4 having rat its outer periphery four downwardly directedcamming portions 5 which are uniformly :distributed about the Aaxis ofthe coaxial `elements 3 and `4. A spring 6, in a manner described below,urges the camming portions 5 against rollers 7 which tare supported forfree rotation respectively about taxes which are perpendicular to and 1-d Y located in a plane normal to the axis of the shlalft 3,

'these rollers 7 being located at equal radial distances from the axisof the shatt 3 and being. displaced with respect to each other by' 90about the axis of the shaft 3. Thu-s, during each revolution of theshaft 3 this Vshaft together with the 'cam 4wi1l be reciprocat'ed back'and forth -along the axis of the shaft 3 fo-ur t-imes. The rollers 7are supported for rotation by the shafts which are in turn carried bythe lower housing part 1 in the manner shown in the drawing. v

.Within the upper housing part 2 is xedly located a cylinder 8 whichforms "the icylinder of the pump, and the spring 6 bears at its upperend, as viewed in the drawing, against a downwardly directed should-'eradjacent the lower end I.of .the cylinder `8, as viewed in the drawing.The other end of the spring 6 bear-s against a washer 9 which is carriedby an upwardly directed shoulder ot an elongated member 10 so that thismember 10 is pressed Y which is convex and which is urged by the spring22 by the spring 6 against the cam 4 and through the member 1'0 thespring 6 maintains the cam 4 yagainst the rollers 7. The cam 4 fixedlycarries an axially extending pin 11 which extends in'to a radial notchformed in the lower end of the member 10, as viewed in lthe :drawing,this radial notch having a width corresponding to the diameter of 'thepin 11, so that as a result with this construction the member 10 isconstrained to rotate and reciprocate with the cam 4. It be noted thatthe member 10 has at its lower-end, as viewed in the drawing,

Va convex end face extending into a recess formed in the upper face ofthe member 4 andengagingthis member 4 in its recess. As will be apparentfrom the description below, the lower solid portion of the member 10shown in the drawing forms a piston means while the upper tubularportion of the member 10 forms a -control means, and of course thecontrol means and the piston means formed by the tubular and solidportions of the member 10 `both reciprocate and rotate as la unit inresponse to the action of the drive means formed by the parts 3 7.

The part of the cylinder 8 in which the tubular portions or controlmeans of the member 10 is located forms the pumping chamber of thecylinder 8, and during reciprocation of the member 10 the piston meansformed bly-the solid portion thereof will reciprocate along pressure`and suction strokes,- asv will be apparent from the description whichfollows. A valve means l12 is located within the tubular portion of themember 10. This tubular portion has a stepped bore. These stepped por-`tions l13, 14, 15 of the tubular part of member 10 have progressivelyincreasing diameters, as shown in the draw-v ing, and the shoulderformed between the portions 14 and 15`of the bore of the tubular portion:of member I10 forms -a Valve seat for the valve means. The valve memberisnprovided beneath the portion thereof which engages the valve lseatwith elongated :guide ns slidably engaging the inner surface of thetubular portion of member 10 in the hone portions 13 and 14 thereof, asshown in the drawing.

A spring 16 for-ms part of the valve means and coopenatesjwith the valve`12, to urge it towand its closed position.` The upper end portion ofthe spring l16, as viewed in the drawing, engages :ajtransverse wall -17'of an elongated-sleeve' member axially slidable within the upper boreportion .15 Vof the member 10, and the sleeve which has the wall '17 hasla very close sliding lit in the lbore portion 15 so as to befluid-tight at its slidable engagement with the member 10. I he sleevehas rat its upper end, as viewed in the drawing, an outwardly directedannular flange 18V which, in the illustrated position of the parts shownin the drawing, engages an inwardly directed y.annular yflange 19 of asleeve 20 which is I.axially slide-ble within the upper housing part 2.A spring 22 which bears at one end against a cover member 23 whichcloses the upper housing part 2 bears at its opposite end against theupper end `of acylind-rical cap member 24 having -a lower lend face,- asviewed in the drawing,

against the transverse wall portion 17, so that the spring 22 maintainsthe cap 2-4 inthe position shown where this cap acts on the wall I17 tomaintain the ange 18 in engagement with the flange 19. Of course, thespring 22 is stronger than the sprin-g 16. Y

The sleeve 20 is formed with a cutout which receives a pin 27 which iseccentrically fixed to an adjusting `member 28. The turnable adjustingmember 28 is supported for turning .movementin a sleeve 29 which -isthreaded into a suitable bore of the upper housing par-t2, and thismember 28 has an outwardly directed flange engaging a shoulder in theinterior of the member 29, as shown in the drawing. To the left of thisange the member 28 has an elongated shaft portion adapted to be turnedin any suitable way 4by ythe operator, zand the sleeve 30 is threadedinto themember 29 and engages the member 28 so as to restrain the member2S againstV axial movement while permitting angular movement thereof.Thus, the operator by adjusting the .angular position :of the member 28will adjust the elevation of the sleeve 2) in the housing 2.

The housing 2 is tormed intermediate its ends with 'an opening 32through which itu-e1 reaches the pump. This opening 32 may be suitablythreaded lso as `to be connected to a suitable conduit leading from anygear pump or the like which pumps iiuel from the tank rto the opening 32so that in this way the duel is delivered to the pump. The cylinder 8 is-formed with aninlet passage means through which iuel lowsto the pumpingchamber in the interior orf the cylinder 8, and this inlet passage meansincludes the annular groove 33 `formed in the exterior of the cylindery8 and the series of openings 34 providing communication between theannular groove 33 and the interior of the cylinder 8. In the illustratedexample there are tour sets of openings 34 displaced by with respect toeach other about fthe axis of the cylinder `8, and in each set ofopenings 3,4 there are three openings located one above the other asillustrated. The control means which is formedby the tubular por; tionof the member 10 is formed with one set of three openings 35 located oneabove the other, and' during reciprocation and rotation of the memberAl() the openings 35 will successively come into communication with thesuccessive sets of openings 34 which are 'distributed about the axis offthe cylinder 8. The angular position of the set ott openings 35 of thecontrol means lformed by the tubular portion of the member lwith respectto the 'four sets of openings 34 which form the inlet passage means issuch that during each suction stroke of the piston means lformed by ythelower part of the member 10, when this member 10 moves downwardly, asviewed in the drawing, the set :of openin-gs 35 communicates with one ofthe sets of openings 34 while during each pressure stroke, when themember 10 moves upwardly, as viewed in the drawing, the set of openings35 is situated between a pair of sets of openings 34 out ofcommunication therewith so thatV in this way the control means opens theinlet passage means during each suction stroke Vand closes the inletpassage means, during each pressure stroke of the piston means.

'IheY upper housing part 2 is termed with (four openings 38 which areintennally threaded so as to be connected with conduits Eleading to theseveral cylinders of the internal combustion engine, and the cylinder 8is formedwith 'a discharge passage means in the form of tour openings 37which respectively communicate with the openings 38 and which arerespectively coaxial there-A with, as indicated in the drawing. |I'hefour openings 37 are also displaced by 90 with respect to each otherabout Y by the tubular portion of the member is additionally formed withen opening 36 which during reciprocation and rotation of the member .10successively comes into and out `of communication with the severalidischange passages 37. The angular position of the opening 36 withrespect to the openings 37 is'such that during each pressure stroke ofthe piston means formed by the lower part of the member 1G the opening36 will communicate with one of the openings 37 while during eachsuction stroke the opening 36 will be situated between and spaced from apair of the openings 37 so that in this way the control means providescommunication between the pumping chamber of the cylinder 8 and thedischarge passage means 37 during each pressure stroke and cuts oncommunication between the pumpingchamber of the cylinder 8 and thedischarge passage means 37 during each suction stroke of the pistonmeans lformed by the lower, solid part of the piston 10.

The parts are shown in the drawing in thev position they take at the endof one of the suction strokes at the point when a succeeding pressurestroke is about to begin. rfhus, at this time the valve means 12 isclosed. During the continued tur-ning of the shaft 3 the member 10 willof course move upwardly so that [the piston means formed by the lowerportion of the member 10 will move along a pressure stroke. As a resultthe valve 12 remains closed and the fuel in the space between the valve12 and the wall 1'7 is compressed. The pressure required to force fuelthrough the injection nozzle of a cylinder :of the internal combustionengine is lgreater .than that required to compress the spring 22 so thatduring the initial part of the pressure stroke the wall 17 together with`a cap 24 rnove upwardly lalong the axis of the cylinder 8. The cap 24is guided for movement by the pin 25 which is carried by the cover 23and which extends through the spring 22, and the cap 24 is capable ofeasily :sliding yaxially along the pin 25. Thus, during the initial partorf the pressure stroke the spring 22 will be compressed, the cap 24 andthe wall 17 will move upwardly, and the volume of the space between fthewall 17 and the valve 12 will remain unchanged so that no fuel will beydisplaced at this time through the discharge passage means. However,before the end of the pressure stroke the cap 24 will engage the bottomend of the pin 25, as viewed in the drawing, so that continued axialdisplacement of elements 17 and 24 will be prevented, and thus at thistime during the continued movement of the piston means along itspressure stroke Kthe valve 12 will approach the wall 17, compressing thespring 16 and forcing fuel out through the discharge passage means.

During the next following suction stroke the opening 36 of the controlmeans Idoes not communicate with any of the openings 37 which form the`discharge passage means, but at this time the set of openings 35 of thecontrol means communicate with fone of the` sets of openings 34` so thatfuel flows into the pumping chamber of the cylinder 8 through theopenings 35 and of course at this time, the valve 12 automatically opensso that the fuel ows into the space between the valve `i2 and the wall17. It will be noted that because :the flange 18 engages the liange 19the wall 17 cannot follow the rnernber 10 during the entire suctionstroke of the piston means formed by the lower portion of the member 10,`so that as a result a suction is created between the lwall 17 and thevalve 12 automatically yopening the valve 12 to admit fuel into thespace between the wall- 17 and the valve 12. At the beginning of thenext following pressure stroke the valve 12 closes automatically, asindicatedjin the drawing. 4 i

It is possible to regulate the amount of fuel displaced -from thecylinder 8 during each pressure stroke by adjusting the angular positionof the adjusting member 28. rfhe maximum amount of fuel will bedelivered by the pump of the invention when the member 2S is turned to iraise the sleeve 20 in opposition to the spring 22 so as to locate thelower end portion of the cap 24 permanently in engagement with thebottom end of the pin 25. As a result duringeach pressure stroke thewall 17 remains stationary and during the entire pressure stroke fuel isdisp-laced out of the injection pump, so that in this Way a maximumamount of fuel may ybe delivered. On the other hand, it is possible toadjust the sleeve 20 so that no fuel will be delivered during eachpressure stroke, `and this can be brought about by displacing the sleeve20 downwardly, as viewed in the drawing, to a position where during theentire pressure stroke the wall 17 will move with the member 1i? withoutremaining stationary while the member 10 continues to move, and thusthere will heno delivery under these conditions.

In order to fully appreciate the invention, the operation of thestructure described above and shown in the drawing without the valvemeans l2 should be considered. If the valve means 12 were omitted thenthere would be no difficulties Vduring operation of the pump at highspeeds. Under these conditions, even if the parts are relatively wornand even ifthe pump operates with a relatively light fuel, the length oftime` that the set of openings 35 remains out of communication with theopenings 34- during each pressure stroke is so short that there is nodanger of leakage of -fuel from the pumping chamber back to the inletpassage means 34. In other words', during high speed operation theresimply is insuflicient'time for the fuel to have an opportunity to leakback to the inlet passage means 34 during each pressure stroke, even ifthe valve means 12 were not present. However, during operation of thepump at a relatively slow speed the fuel could leak back to the inletpassage means 34 during each pressure stroke. The distance between theset of openings 35 and any one of the sets of inlet openings 34 at anygiven moment is at a maximum extremely small. Therefore, duringrelatively slow speed operation under certain conditions as when thepump operates with a relatively light fuel or when the parts becomerelatively worn, the fuel which is under relatively high -pressure inthe pumping chamber could indeed leak back between the surfaces of thecylinder 8 and the member 1d to the inlet passage means 34. If thedistance between the set of openings 35 and the sets of openings 34 weremade great enough to prevent this result from happening, the `diameterof the cylinder 8 and the member 19 would be so large that the injectionpump would have no practical utility. Therefore, under these conditionsthe valve means 12 functions to prevent leakage back to the inletpassagemeans 34. `Because ofthe presence of the valve means 12 it is notpossible for fuel between the valve l2 and the wall 17 to leak back tothe inlet passages 34 during each pressure stroke. On the other hand,during high speed operation the inertia of the valve 12 is such that itcannot become seated and unseated withthe precision and with thesynchronism which is required. In other words, because of the inertiaeffects resulting from the high speed reciprocation and rotation of themember lil the member 12 during high speed operation cannot reliablyremain on its seat in a closed position during the entire part of eachpressure stroke. However, this is immaterial since the openings 35` atthis time cooperatewith the discharge passages 34 to prevent the fuelfrom reaching the inlet passages 34. Therefore, while retaining all ofthe advantages of an injection pump designed for high speed operation,the addition of the valve 12 enables the structure also to operate in aperfectly satisfactory vmanner even under low speed operating conditions`and even with relatively light fuels and even after within the cylinder8.

the parts have been relatively worn so that the seal between theexterior surface of the member 10 and the inner surface of the cylinderS is not absolutely fluid-tight at the high pressure prevailing during apressure stroke lt will be noted also that with the structure of theinvention the disadvantage of not being able to use a pump designed forlow speed operation also at high speed operation is avoided, so that inthis way with the structure of the invention the same pump can be usedfor operation both at low speeds and high speeds and with all type offuel as Well'as under all operating conditions.

The injection pump of the invention is particularly suitable for usewith light fuels and high speed Otto engines. Such fuels because oftheir low viscosity require an effective structure for preventingleakage back vto the inlet of the pump from the pumping chamber.However, the injection Vpump of the invention is also equally wellvsuited for operation with other fuels.

It will be understood that each of the elements described above, or twoor more together, may also find a useful applicationin other types ofpumps differing from the types described above.

While the invention has been illustrated and described as embodied ininjection pumps, it is not intended to be limited to the details shown,since various modiiications `and structural changes may be made' Withoutydeparting in any way from the spirit of the present invention.

Without further analysis, the 'foregoing will so fully reveal the gistof the present invention that others can by applying current knowledgereadily adapt it for various Y applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics Vof 'the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In an injection pump, in combination, a cylinder having a pumpingchamber therein; piston means in said cylinder Vadapted to reciprocatetherein along pressure and suction strokes; inlet passage means Vleadingto said pump- :ing chamber; discharge passage means leading from saidvpumping chamber; control means connected to said piston means formovement therewith and cooperating with said inlet and discharge passagemeans for opening said inlet passage means during each suction stroke ofsaid piston means and for closing said inlet passage means during eachpressure stroke of said piston means, said control means opening saiddischarge passage means during each pressure stroke of said piston meansand closing said discharge passage means 'during each suction stroke ofsaid piston means, said control means .being capable of preventingleakage of fuel back to said inlet passage means duringth'e pressurestrokes of said piston means when the pump operates at relatively highspeeds but under certain operating conditions, as when the pump is usedAwith a relatively light fuel or when the parts become Worn, beingincapable of preventing leakage of fuel back to said inlet passage meansduring pressure strokes Vof said piston means when the pump `operates atrelatively slow speeds; and valve means carried by said control meansfor movement therewith and located in the path of flow of fuel .fromsaid inlet passage means to VVsaid pumping chamber for preventing fuelyfrom leaking bac-kto said inlet passage means during pressure strokesof 'said vpistorrmeans at relatively slow speeds of operation of thepump, said valve means, because of its inertia, being incapable ofmaintaining the pumping chamber closed off from said inlet passage meansduring the entire pressure strokes of said piston means when the pumpoperates at relatively high speeds, whereby said con- Y trol means andsaid 'valve means cooperate to prevent vleakage back to saidinletpassage means yduring all speeds jof operation of the pump.

2. In an injection pump which is adapted to operate vat relatively Ilowas well as at relatively high speeds, in combination, acylinder having apumping chamber; piston means located in sai-d cylinder and adapted toreciprocate therein along pressure and suction strokes; inlet passagemeans providing a path of fuel ilow into said 'F62 w pumping chamber;4discharge passage means providing -a path of fuel flow out of saidpumping chamber; control means connected to sai-d piston means formovement therewith and cooperating with said cylinder for opening saidinlet passage means during each suction stroke of said piston means and-for closing said inlet passage means during each pressure stroke ofsaid piston means, said control means opening said discharge passagemeans during each pressure stroke of said piston ymeans and closing saiddischarge passage means during each suction stroke of said piston meansand said control means, under certain operating conditions as when theYpump operates with -a relatively light fuel or when theparts becomerelatively worn, being incapable of preventing leakage of -fuel duringpressure strokes of said piston means back to'said inlet passage meansat relatively low speeds of operation of the pump; :and valve meanscarried 'by 4said control means for lmovement therewith and locatedbetween said inlet passage means and said pumping lchamber forpreventing flow of fuel back to sai-d inlet passage means duringpressure strokes of said piston means at relatively low speeds ofoperation of the pump, said valve means, because of its inertia, beingincapable of maintaining said inlet passage means closed off from saidpumping chamber during the entire pressure strokes of said piston meanswhen said pump operates at relatively high speeds, whereby said controlmeans land said valve means cooperate to prevent leakage of fuel back tosaid inlet ,passage means during pressure strokes of said piston `meansat relatively low as well as at relatively high speeds of openation ofthe pump.

3. In an injection pump adapted to operate at relatively low as well asat relatively high speeds, in combination, a cylinder having a pumpingchamber and formed with a pair of passages extending through the wall ofsaid cylinder and axially displaced with respect to each other,one ofsaid passages forming an inlet passage providing for a path of fuel`flow into the pumping chamber and the other of said passages forming adischarge passage providing for a path of fuel flow out .of said pumpingchamber; an elongated member slidably located in said cylinder andhaving one portion which forms a piston means and another portion formedwith a pair vof passages cooperating respectively with said pair ofpassages of said cylinder and forming a control means for controllingthe opening and closing of said cylinder passages; means cooperatingwith said elongated member for axially reciprocating the same and forrotating the same in said cylinder so that the portion of said memberwhich forms said piston means will reciprocate in said cylinder alongpressure and suction strokes and the portion of said member which formsa control means will cooperate with said cylinder passages to close saidinlet passage during each pressure stroke of said piston means and toopen said inlet passage during each suction stroke of said piston means,said control means cooperating with said discharge passage for closingthe'A latter during each suction stroke of said piston means and foropening said discharge passage during each pressure stroke of saidpiston means, and said member, under certain operating conditions aswhen the pump works with a relatively light fuel or when the partsbecome relatively worn, being incapable of preventing the leakage offuel from said pumping chamber back to said inlet passage during eachpressure stroke of said piston means of its inertia being incapable ofreliably closing offV the pumping chamber from said inlet passage duringthe entire part of each pressure stroke of saidpiston means when Ithepump operates at relatively high speeds, whereby the valve means and thecontrol means cooperate to prevent the llow of fuel back to said inletpassage means during each pressure stroke of said piston means when thepump operates at relatively low -speeds as well as when fthe pumpoperates at relatively high speeds.

4. In an injection pump capable of operating at relatively -low as 'welllas at relatively high speeds, in combination, a cylinder having apumping chamber in its interior and formed in its wall with an inletpassage means providing for iuel flow into said pumping chamber and,axially spaced from said inlet passage means, with a discharge passagemeans providing for fuel ow out of said `pumping chamber; an elongatedmember slidable in said cylinder, having a tubular portion in saidpumping chamber and overlapping both of said passage means and having asolid portion next to said tubular portion, lsaid solid portion yforming'a piston means and said tubular por-tion of said elongated member beingformed with passages cooperating with said inlet .and dischange passagemeans and forming a control means; drive means cooperating with saidmember -for reciprocating and rotating the same i in said cylinder, saidpiston means reciprocating along pressure and suction strokes when saidmember is reciprocated by said drive means and said control meanscooperating during driving 4of said member with said inlet and dischargepassage means for lclos-ing said inlet passage means duning each suctionstroke of said piston means and for opening said inlet passage meansduring each suction stroke of said piston means, said control meanscooperating with said discharge passage means kfor closing saiddischarge passage means during each suction stroke of said piston meansand for opening said discharge passage means during each pressure strokeof said piston means, Yand said member, under ce1-tain operatingconditions as when the pump 4operates with a relatively light fuel orwhen the parts become relatively worn, being incapable of preventingleakage of fuel back to said inlet passage mean-s during pressurestrokes of said pistonV l means when the pump operates at a relativelylow speed;

and valve means located in said tubular portion of said member betweenthe passage thereof which cooperates with said ydischarge passage meansand the passage there or" which cooeprates with said inlet passage means`for closing off the pumping chamber ,from said inlet passage meansyduring pressure strokes of said piston means when the pump operates atrelatively low speeds, said valve means, because of its inertia duringreciprocation land rotation lof said member when the pump operates atrelatively high speeds, being ineapable of maintaining said pumpingchamber closed olf from said inlet passage means during the entire partof each pressure stroke of piston means when the pump operates atrelatively high speeds, whereby said control means and valve meanscooperate to prevent leakage of fuel back to inlet passage means duringboth relatively high and relatively low speeds of operation of the pump.

5. In an injection pump as recited in claim 4, said tubular portion ofsaid member being formed in its interior with a shoulder providing avalve seat for the valve means.

5 inlet passage means, with a dischange passage means providing for tlowof fuel `out vof said pumping chamber; an elongated member slidablylocated in said cylinder and means cooperating with said member forreciprocating yand rotating the same in said cylinder, said elongatedmember having one portion which extends transversely across saidcylinder 'and forms a piston means which reciprocates therein alongpressure land suction strokes and having another portion which istubular and which is formed Iwith passages which during rotation of saidelongated member open said inlet passage means during each suctionstroke :of said piston means and closes said inlet passage means duringeach pressure stroke of said piston means and which during each pressurestroke of said piston means opens said discharge passage means of saidcylinder and closes said dischange passage means during each suctionstroke of said piston means, said elongated member, under certainoperating conditions as when the pump operates with a relatively lightfuel or when the part-s become relatively worn, being incapable ofpreventing leakage of `fuel back to said inlet passage means dur-ingpressure strokes of said piston means when the pump operates atrelatively low speeds, said ltubular portion of said member being formedin its interior with an axial, stepped bore having intermediate its endsa shoulder located between the part of said tubul-ar portion whichcooperates with said discharge passage means and the part thereof whichcooperates with said inlet passage means and said shoulder forming avalve seat; a valve member guided in said Itubular portion for axialmovement between open and closed positions and engaging said valve seatin its closed position, said valve member engaging said valve seatduring each pressure stroke of said piston means when the pump operatesat relatively low speeds so as to cut olf the pumping chamber from saidinlet passage means at low speeds of operation of the pump, and saidvalve member due to its inertia, when rotating and reciprocating withsaid elongated member during oper-ation of .the pump at relatively highspeeds, being incapable of remaining on said valve seat during theentire part of each pressure stroke of said piston means when the pumpoperates at high speeds, whereby said tubular portion of said elongatedmember and said valve member cooperate to prevent flow of fuel ,back tosaid inlet passage means during both low and high speeds of operation ofthe pump.

7. In a pump as recited in claim 6, means cooperating with said cylinderfor controlling the volume of said pumping chamber so as to regulate the`amount of fuel 5' discharged therefrom during each pressure stroke ofsaid piston means.

References Cited in the iile of this patent UNITED STATES PATENTSAldinger Mar. 15, 1960

1. IN AN INJECTION PUMP, IN COMBINATION, A CYLINDER HAVING A PUMPING CHAMBER THEREIN; PISTON MEANS IN SAID CYLINDER ADAPTED TO RECIPROCATE THEREIN ALONG PRESSURE AND SUCTION STROKES; INLET PASSAGE MEANS LEADING TO SAID PUMPING CHAMBER; DISCHARGE PASSAGE MEANS LEADING FROM SAID PUMPING CHAMBER; CONTROL MEANS CONNECTED TO SAID PISTON MEANS FOR MOVEMENT THEREWITH AND COOPERATING WITH SAID INLET AND DISCHARGE PASSAGE MEANS FOR OPENING SAID INLET PASSAGE MEANS DURING EACH SUCTION STROKE OF SAID PISTON MEANS AND FOR CLOSING SAID INLET PASSAGE MEANS DURING EACH PRESSURE STROKE OF SAID PISTON MEANS, SAID CONTROL MEANS OPENING SAID DISCHARGE PASSAGE MEANS DURING EACH PRESSURE STROKE OF SAID PISTON MEANS AND CLOSING SAID DISCHARGE PASSAGE MEANS DURING EACH SUCTION STROKE OF SAID PISTON MEANS, SAID CONTROL MEANS BEING CAPABLE OF PREVENTING LEAKAGE OF FUEL BACK TO SAID INLET PASSAGE MEANS DURING THE PRESSURE STROKES OF SAID PISTON MEANS WHEN THE PUMP OPERATES AT RELATIVELY HIGH SPEEDS BUT UNDER CERTAIN OPERATING CONDITIONS, AS WHEN THE PUMP IS USED WITH A RELATIVELY LIGHT FUEL OR WHEN THE PARTS BECOME WORN, BEING INCAPABLE OF PREVENTING LEAKAGE OF FUEL BACK TO SAID INLET PASSAGE MEANS DURING PRESSURE STROKES OF SAID PISTON MEANS WHEN THE PUMP OPERATES AT RELATIVELY SLOW SPEEDS; AND VALVE MEANS CARRIED BY SAID CONTROL MEANS FOR MOVEMENT THEREWITH AND LOCATED IN THE PATH OF FLOW OF FUEL FROM SAID INLET PASSAGE MEANS TO SAID PUMPING CHAMBER FOR PREVENTING FUEL FROM LEAKING BACK TO SAID INLET PASSAGE MEANS DURING PRESSURE STROKES 